THE vastness of Earth's oceans and the limited extent of our knowledge and occupation of them often invites comparisons with space. But they are much more attainable than the moon or Mars. Hence the enduring fascination with "seasteading", the idea of building permanent settlements at sea (see "Brave new sea worlds to redefine society").

Those who push the idea are often dismissed as libertarian fantasists. The seasteading movement has its fair share of those, but it is also home to pioneers longing to conquer a new frontier.